Differential responses of crop pollen microbial communities to insect visitation and host identity: fungi are more sensitive than bacteria

Introduction In the pollination process, pollen serves not only as a key vehicle for plant reproductive success but also as an important ecological interface for microbial transmission and selection. However, how insect visitation and host plant identity jointly affect the assembly of pollen microbial communities in agroecosystems remains poorly understood. Methods Here, we employed bagging and open-pollination treatments combined with high-throughput sequencing to investigate the effects of insect visitation and host plant identity on the structure, composition, diversity, interspecific interactions, and core taxa of pollen microbial communities in crops. Results Results showed that insect visitation and host plant identity jointly and significantly influenced the structure of pollen bacterial asnd fungal communities and altered their taxonomic composition, diversity, and interaction patterns, with these effects being mainly evident in cross-pollinated plants and more pronounced in fungal than in bacterial communities. Further analyses revealed that insect visitation increased network connectivity while reducing modularity (0.046) in bacterial communities of cross-pollinated plants, whereas their fungal network exhibited reduced connectivity and increased modularity (0.787). In cross-pollinated plants, fungal core taxa dominated the fungal communities (>87%), while bacterial core taxa contributed relatively little to overall community. Dicussion/conclusion Overall, insect visitation and host plant identity jointly shape pollen microbial communities, but bacterial and fungal communities exhibit distinct response patterns, with bacterial communities being relatively stable and fungal communities being more sensitive. This study highlights the key roles of insect visitation and host plant identity in pollen microbiome assembly and provides a theoretical basis for understanding crop pollination ecology and plant–pollinator–microbe interactions.